Aluminosilicate Cement Sheath Resisting CO2 Degradation
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Solution Overview
Problem
Conventional cement compositions used in subterranean operations are susceptible to degradation in carbon dioxide-rich zones, leading to compromised mechanical and hydraulic properties, which can result in loss of zonal isolation and potential well failure.
Innovation Solution
Cement compositions comprising aluminosilicates, sodium aluminate, calcium aluminate, and water are introduced into subterranean formations, setting to form sheaths resistant to carbon dioxide-induced degradation, without using Portland cement, thereby maintaining integrity and preventing chemical alteration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Portland-based cement is used in subterranean operations, then initial strength and setting properties are improved, but resistance to CO2-induced degradation deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the cement by replacing Portland cement with a blend of Class F fly ash, metakaolin, and calcium aluminate cement. This substitution fundamentally alters the cement's chemical reactivity toward CO2 while maintaining adequate strength through the synergistic pozzolanic reactions of the alternative materials.
Solution Approach 2:
The invention uses a composite cement system combining Class F fly ash, metakaolin, and calcium aluminate cement. This composite material leverages the complementary properties of each component: fly ash provides long-term strength and low permeability, metakaolin offers rapid early strength and fine pore structure, and calcium aluminate cement delivers CO2 resistance and early strength, achieving both strength and reliability requirements.
2Ease of manufacture
If conventional cement compositions are used in CO2-rich zones, then ease of manufacture is improved, but chemical stability deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters by substituting Portland cement with alternative materials that have different reactivity profiles. Class F fly ash, metakaolin, and calcium aluminate cement collectively provide chemical stability in CO2-rich environments while maintaining manufacturability through standard cementing equipment and procedures.
Solution Approach 2:
The invention employs Class F fly ash, a readily available and inexpensive byproduct material, as a primary component. This economical choice reduces manufacturing costs while the combination with metakaolin and calcium aluminate cement ensures sufficient chemical stability, making the solution both economically viable and technically effective.
3Loss of time
If Portland cement is used to form cement sheath, then initial setting time is reduced, but long-term hydraulic seal integrity deteriorates
Solution Approach 1:
The patent incorporates metakaolin, which provides rapid early strength development and quick initial setting. This preliminary action establishes the cement sheath structure quickly, while the subsequent pozzolanic reactions of fly ash and calcium aluminate cement continue to strengthen the material over time, ensuring long-term hydraulic seal integrity.
Solution Approach 2:
The composite cement system combines materials with different setting and strength development characteristics. Metakaolin contributes rapid early strength for quick setting, while Class F fly ash provides progressive strength gain and low permeability over time, and calcium aluminate cement ensures chemical stability. This composite approach achieves both rapid setting and long-term seal integrity.
4Quantity of substance
If cement sheath is exposed to CO2-rich environment, then porosity increases, but resistance to chemical alteration deteriorates
Solution Approach 1:
The patent changes the chemical composition to use Class F fly ash, metakaolin, and calcium aluminate cement instead of Portland cement. This substitution alters the mineralogical composition and reaction products, creating a cement sheath with lower porosity and reduced susceptibility to CO2-induced chemical alteration, thereby improving resistance while controlling porosity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a robust cement sheath resistant to CO2-based degradation, maintaining compressive and shear bond strength, and preventing porosity and permeability increases, thus ensuring efficient zonal isolation and prolonged well operation.
Implementation Method 1
cement compositions comprising aluminosilicates, at least one of a sodium aluminate and a calcium aluminate, and water... set cement sheath is resistant to degradation to corrosive components within the subterranean formation
Data Source
AI summary
Cement compositions may comprise an aluminosilicate; a sodium aluminate, a calcium aluminate, a potassium aluminate, or a combination thereof; and water. In some cases, the cement does not include Portland cement. The cement may be used in a subterranean formation having corrosive components therein, wherein the set cement sheath is resistant to degradation from the corrosive components within the subterranean formation.